Electrical

Question 1

What are the AC generators rated at?

Answer 1

115 volt, 400 hertz, 3-phase

Question 2

What are the electrical system’s 3 distribution systems?

Answer 2

1. ) AC Power Distribution
2. ) DC Power Distribution
3. ) Emergency Power Distribution

Question 3

What changes AC to DC power?

Answer 3

Transformer-Rectifiers

Question 4

Is the emergency power distribution system part of the normal electrical power distribution system?

Answer 4

Yes, it uses both AC and DC power

Question 5

In the event of loss of normal AC and DC power, what is the emergency power distribution system powered by?

Answer 5

Aircraft Batteries

Question 6

Where does the Ground Service Bus receive power from?

Answer 6

Right Generator Bus, APU, or External Power

Question 7

What are the 4 types of generator faults?

Answer 7

Over or Under Voltage

Over or Under Frequency

Question 8

What is needed for the battery charger to work?

Answer 8

Batter charger must “BEG” to get powered:

B- Battery switch must be on

E- Emergency Power switch must be off

G- Ground Services Bus must be powered

Question 9

Items on the Battery Direct Bus

Answer 9

BRACES:
B- Battery Relay

R- Refueling Panel (Ground) and Valves

A- Aircraft Clock

C- Charger and Transfer Relay

E- Emergency DC Bus/Emergency Inverter

S- Stairs Forward (not installed on our fleet)

Question 10

Items on the Battery Bus (Batt ON)

Answer 10

Triple A's D's:
A- APU Control
A- APU EGT
A- AC Emergency Bus off light
D- DC Emergency Bus off light
D- DC Transfer Bus off light (OAP only)

Question 11

Major Items on the Left Gen Bus

Answer 11

PHANG:
P- Pack Fan Left
H- Hydraulic Aux Pump
A- AC Bus Left
N- Normal Pitch Trim (Primary-Motor)
G- Galley Power

Question 12

Major Items on the Right Gen Bus

Answer 12

P-GAG:
P- Pack Fan Right
G- Ground Services Bus-> Batt Charger & Rt T/R
A- AC Bus Right
G- Galley Power

Question 13

“EXT PWR AVAIL” light means what?

Answer 13

Correct phase supplied and at least 95 volts

Question 14

DC Transfer Bus Pwr Supply priority:

Answer 14

1. ) Left DC Bus
2. ) Right DC Bus
3. ) Aircraft Battery
4. ) Ground Service Bus (Rt Gen Bus not powered)

Question 15

What is considered a System Fault?

Answer 15

GPS:
G- Generator Bus fault (Short)
P- Phase imbalance
S- Supply Feed fault (short between Gen and Bus)

Question 16

Items on DC Transfer Bus (Batt ON):

Answer 16

SAFES*:
S- Start Pump DC (Fuel)
A- APU Door Control
F- Fire Protection & Detection + Master Caution/Warning
E- Eng Start switch & Eng Start Valve
S- Standby Horizon
* Left EOAP

Question 17

AC Power Source Priority:

Answer 17

1. ) Respective Eng Gen
2. ) APU Gen
3. ) External Power
4. ) Operating Gen through the AC Crosstie Relay

Question 18

Items remaining while on Emergency AC

Answer 18

Captain Navigates and controls Heat

ADI/PFD, HSI/ND, VSI, Altimter, F/O Compass, #1 NAV, #1 CADC, #1 Symbol Generator, Manual Temp Control

Question 19

Items remaining while on Emergency DC

Answer 19

Crew talks, breathes, and can see heat
#1 Comm, #1 Glideslope, P.A., Interphone, Stby Lights, Air Conditioning flow and pressure valves, Cpt's Pitot Heat, EGT

Question 20

What happens in the event of a system fault?

Answer 20

The GCR, GR, and ACTR will all open. This will isolate the respective Gen Bus and AC Bus from any power source.

Question 21

What annunciators will illuminate with a system fault?

Answer 21

L/R GEN OFF, L/R AC BUS OFF, DC BUS OFF, AC CROSSTIE LOCKOUT

Question 22

How many batteries does the electrical system have? Volts?

Answer 22

Two 14 volt NiCad batteries connected in series = 28 volts

Question 23

How long will emergency power supply the system?

Answer 23

30 minutes minimum

Question 24

Which buses will remain powered while on emergency power?

Answer 24

1. ) AC Emergency Bus
2. ) DC Emergency Bus
3. ) DC Transfer Bus
4. ) Battery Bus
5. ) Battery Direct Bus

Question 25

Where does the AC Emergency Bus normally get its power from?

Answer 25

The left AC Bus through the AC Emergency Power Transfer Relay (AEPTR)

Question 26

Where does the DC Emergency Bus normally get its power from?

Answer 26

The left DC Bus through the DC Emergency Power Transfer Relay (DEPTR)

Question 27

When will the DC Transfer Bus be powered by the batteries?

Answer 27

With the:
1.) BATT Switch- On

2. ) AC Ground Service Bus- Not powered
3. ) Neither DC Bus powered

Question 28

Which system does AEPTR and DEPTR normally connect to? What about in a failure?

Answer 28

Left electrical system

In a failure of the left system it’s spring loaded to the right

Question 29

Other than operating on battery power, what else will happen with the EMER PWR switch ON?

Answer 29

• EMER PWR IN USE light illuminates
• cabin standby lights illuminate
• output of the battery charger is disconnected from the batteries

Question 30

What is a CSD? What does it do?

Answer 30

Constant Speed Drive, it allows the generator to operate at a constant speed independent of engine RPM

Question 31

What will the CSD DISC Switches do?

Answer 31

Will disconnect the CSD from the engine drive assembly provided the engine N2 RPM is above 25%

Question 32

What does the L/R Gen switch Reset do?

Answer 32

Resets the Generator Control Relay (GCR)

Question 33

On the Ground Service Electric PWR panel, what happens if both the APU PWR and EXT PWR switches are selected to ON?

Answer 33

They cancel each other out and neither will supply PWR.